Doulames, V., Lee, S., Shea, T. B. 2014. Environmental enrichment and social interaction improve cognitive function and decrease reactive oxidative species in normal adult mice. International Journal of Neuroscience 124(5), 369-376.

Environmental stimulation and increased social interactions stimulate cognitive performance, while decrease in these parameters can exacerbate cognitive decline as a function of illness, injury, or age. We examined the impact of environmental stimulation and social interactions on cognitive performance in healthy adult C57B1/6J mice. Mice were housed for 1 month individually or in groups of three (to prevent or allow social interaction) in either a standard environment (SE) or an enlarged cage containing nesting material and items classically utilized to stimulate exploration and activity (“enriched environment”; EE). Cognitive performance was tested by Y maze navigation and Novel Object Recognition (NOR; which compares the relative amount of time mice spent investigating a novel vs. a familiar object). Mice maintained for 1 month under isolated conditions in the SE statistically declined in performance versus baseline in the Y maze (p< 0.02; ANOVA). Performance under all other conditions did not change from baseline. Maintenance in groups in the SE statistically improved NOR (p < 0.01), whereas maintenance in isolation in the SE did not alter performance from baseline. Maintenance in the EE statistically improved performance in NOR for mice housed in groups and individually (p < 0.01). Maintenance under isolated conditions slightly increased reactive oxygen/nitrogen species (ROS/RNS) in brain. Environmental enrichment did not influence ROS/RNS. These findings indicate that environmental and social enrichment can positively influence cognitive performance in healthy adult mice, and support the notion that proactive approaches may delay age-related cognitive decline.